Engine piston construction



Oct. 2, 1945. R. M. H VlE 2,386,117

ENGINE PISTON CONSTRUCTION Filed Dec. 29, 1943 fivezzor: Ems K553 Patented Oct. 2, 1945 v renam- QFF QE jro icossrnw v-msi fi-s i Wrasse/Il xrini qoii naneqemher 2 19.43, SQ IiaLN 1 in 1 g ue My invention relatesito engineipistons.andmore particularly. to i pistons .for .internal comhust fi engines and for; other types of machinery. inwhich cylinders and.pistons arelemployediin, ,co 3nection with the i compressing or expanding oft gases,

In the. following description, I na-k. inventigni is illustrated andgegiplainednino connection: With a pistondesignedion use ;in.,a ifourvsbmke, cycle in: ternal combustion engine OfitheivertioaLtype with the.-., cy1indeir @aboverthe crankshaft, but ,it, is obvious that. my invention may. be. utilized. in. o her forms ofenginesiorimotors;

'frhe present rpracigioe is to equip .pisipus with seyeral,suitabiy,designed andimanu aq ureahis: ton rin s Theseirings are placed neroo esicut in, the outerwcireumferenee of. the-piston e ror are located. near therupneriuorihead, emiro o hei isr ton. The. rings arerde i ned to iexertssufiiaielit outward vradial pressure pnntheginte or of, theicylinderiwall so,-.as toe-prevent. A passing. etween hth tiouterisuriaces .of; th ndithe yll nde nnersur a e ari the engine, is in operati n nsqq i t' sel i-theseipiston; rinss.. ne =9 m desisnedcil soraneroringsiare lsove ieail ap; plied o t e P st n h roi QraD r-- in e placed in grooves, similar to the gr es re ing thepiston rings, but whichare nearerito the lower, oropen, end -of the piston head. Itis the function of the oil; scraper rings to scrape f the. e ess. lub ic t n i mm he int ri r surfaceof, the icylin kier, thus p ting the oil, s far p s i e, rQm-. ns qarriedim-fiqn h om us a e: o h hei vl oqe v. by thamotion of thep sto iandq r t n this .o l- .to. heorems: case of thesengine for,re usg perie c as hown thatithei isi hs ia h i r t, s e r b d bove, faulty-1 other ere ar no p st n in s esiarasil miaware, whi it I nV i-saidi ha i t ey are p rfe tly sastisht, r subst ntially: ast ht, ine per on er nv e tended eriod n s Q nf mart n: p r asons .Q th siault, is shat-in p stons a owi nu iured, it i imp ss le QEPKWQP-Efifi-S dur n th .cqmpress n-anunew rsi ei is i i- 11i: pi onsiwm assin s etween heitonho imnta urf g pi he Paw r sendihesubiei lin i o rf i r gr pveepd i 1 9 he.., =l r. ce ace e nside n j-vhe ston in idi v h r r j erin i nsl risiqni nieane bet n swhen? ace-and he ,b12 .1 b m surface in the ring groove to t h serves as meanslior drainage o f' iexqess l ubr c 9 bearings 6 and-iiandsurroundin fect.. The pistonring .nearestitheiopgof ,thehhead of the .LpiStOn,iS thatLWhiCh;Cal/1865.113118111051 101 hie; Beingwlocatedlin the,.i1ighst and;i mfite portion :of T the ."pistonia'nd exposed vdir lut yitqthe 52 burning. gases, lit is .nbt possible. to .lubr cate this early part of thepowerstrokethisaringjs foroeo radially gagainste theulinterion surface ,ofiwthe icy inder wall-thy; a veryrhigh gas pressure, ano as lubrication at this part of the piston strolge is practically nonexisting,,the ring,,the ring groove and ,i the cylinderwwall are; subject. ,to ory; great wear. The. present; inventionv cQ r Qts the defect described above. Other advantages o11m ggnven tion will vbe pointed out hereinafter,

For .a b tter understandin ft theineti z i @9 cope o m i nt on r fer nce axiheoheda the. ollowing descriptio ndntheuaci pmnanyie drawing, iw1' 1e rei n1 1 i Fig.1 is a ;vi,e,w, p rtiall inie eva iqnt nd Pan tiallyw in cross section, of a piston embogyingone form of mysi v ntion thiss iqwqbe .suiakfii throu hthe c n er l n Qfithe-wri i Pi Fi -2J8 is l n iew the pt olnlpii hd i tom, .of Fi .1 1 show n he. pen: en we ens? contoursi oss sand.bo es;

39 Fig- 3 is a side elevation of the piston, taig n at 99?: tothev ew ofi is-li t Ji -1 3s an enlarged ossrse ti ialfliew;be

ontheiine rlp F i nd 7 an, exp od d, er nee ivet ew ft-3 3.5 composi i ie i-r ns whit sh: r l iiz ia IfQr' 1$? p sfioii iston r nss rea s oebe- Refer in o th fi tes. his ih w' iQ 1x the piston ring groove ;3.is.t he pistorr g- 4 with thepistoniof imy present invention. Other .9 is t e ear nceii ce iii i i i nsi e h stonl e 3*. a.;ise e i here er ere ef ab e nde i ni cressfieqi ni Wl' he route mumf en of P iefi nw a; t eethenwi r ri le h :b?- P-, ?WJ I 3 cylinder wallm y ithe pistonring 3. H 6 and li are 1 the hearin'gs the, piston for a. hollp 16;; I-,-anc1 Share annular oil gro ov i6 8 and 8 are vertical bores tem (L n bqsse 89 G 11 he Pe 1 .1 tiglf ly ili ihiixb 8 -1 fl i id flia plu s sliilv ii tin e hxesee i 3 8 and 8, as shown in Fig. 1. II and II are valve seats, formed on the top of the screw plugs III for ball check valves I2 and I2. The valve seats II are formed on the edges of the central holes in the screw plugs I and I0. I3 and I3 are springs which normally press the ball check valves I2 and I2 against their valve seats II-I I. I4 and I4 are drilled passages connecting the spaces above and surrounding the ball check valves I2 and I2 with the clearance space 4 inside of the piston ring 3. I

The interior space I5 formed in the hollow Wrist pin I6 is tightly closed by screw plugs I! and I1. Through the wall of the hollow wrist pin I6 are drilled oil holes I8, I8 and I9. Oil holes I8 and I8 connect the hollow space I5 in the wrist pin with the annular grooves I and I. Theoil hole I9 is located midway between the ends'of wrist pin I6. The wrist pin I6 has a so-called floating fit in wrist pin bearings 6 and 6 in the piston.

Only the piston end of a connecting rod is illustrated in Fig. l, as that part only is required for describing my invention. The connecting rod 20 is fitted with a wrist pin bearing 2| of the usual type and having a running fit on the hollow wrist pin I6. Midway from both ends of this bearing and communicating with the hole I9, an annular groove 22 is cut in the boss of the rod 20. This groove surrounds the wrist pin, and a threaded opening 23 is made in the top end of the connecting rod 20 which opens into the annular groove 22. A spray nozzle 24 is screwed into threaded opening 23 as shown.

A drilled hole 25 is formed in the connecting rod 20 that extends from the crank pin bearing in the lower end of the rod, not shown, into the annular groove 22. v

It is apparent that except when ball check than the force or pressure of the oil to open the ball check valves I 2 and I2, said check valves open and permit the oil to pass on through the drilled passages l4 and I4 into the clearance space 4 adjacent to the inside surface of the piston ring 3.

During the period in the power cycle in which the gas pressure in the cylinder exceeds the pres sure of the oil entering clearance space 4, check valves I2 and I2 of course remain closed, thus looking a body of oil in the clearance space 4. The gas pressure now acts upon the oil contained in the clearance space 4 by entering into space 4 through the small clearance between the upper face of piston ring 3 and its adjacent face in the valves I2 and I2 are spring-pressed onto their valve seats II and II, there is a clear passage from the crank pin bearing in the lower end of the connecting rod 20 to the clearance space 4 on the inside of the piston ring 3, this passage comprising the hole 25, the hole I9, the chamber I5, the holes IB, the bores 8, and the bores I4.

Referring to Fig. 4, this illustration shows certain detailsof the piston head on a larger scale. At 26. is indicated that theoutside diameter of the piston I is there somewhat reduced. This is done in order that excess oil on the interior surface of the cylinder wall, scraped oif by the sharp, corner 21 on piston rin 3, may find room enough to flow into groove 4a for return to the engine crankcase through the drain holes 5. Edge 28 on the piston ring is suitably rounded or beveled in order that the piston ring 3, when the piston moves upwards in the cylinder, will not scrape the lubricating oil film off the inner cylinder surface, but will glide on it with minimum friction.

Having now described the piston and details embodying my invention, it is readily understood that when the engine is in operation the engines lubricating oil pump (not shown) forces lubricating ,oil from the crank pin bearing to the wrist pin bearings through drilled hole 25 in the connecting rod 20. A part of the oil thus supplied under pressure is diverted to the spray nozzle 24 Another part of the oil supply is forced upwardly through the openings I8IB andinto the bores 8 and 8 andwhen, during each power cycle in the engine the resistance to opening is less ring groove, thus forcing a filmlike quantity of oil from clearance space 4 through the small clearance between the lower ring'face and its adjacent face in the ring groove and onto the inner surface of the cylinder.

It is intended that the volume of clearance space 4 be determined in such a manner that during the operation of the engine a, certain amount of oil will always remain in it after a discharge period. As the gas pressure can only enter clearance space 4 over the upper face of the piston ring 3, it is therefore now impossible for gas to pass by the piston ring by going through the clearance space 4 on the inside of the ring and. escaping under the ring 3.

During the period in the power cycle in which the gas pressure in the cylinder is low, so that the oil pressure under check valves I2 and I2 is greater than the load on top of. these valves, oil under pressure passes by the then open ball check valves I2 and enters the clearance space 4, thus filling it and exerting an outward radial pressure upon the inside of the piston ring 3. Oil leakage from clearance space 4, due to the oil pressure obtaining in this space, can now take place over and underthe piston ring 3 and onto the interior surface of the cylinder wall. It will be observed that also during this period in the power cycle there is no opportunity for gas leakage past the piston ring 3. It is obvious that machinery employing cylinders with pistons and details embodying my invention will be substantially gas tight in operation.

Thorough lubrication of the piston, piston ring, ring groove and interior surface of the cylinder is obtained by means of the present invention and the cooling'and cleaning'eifect of the lubricating oil supplied in the manner described is greatly beneficial to good operation and long wear. Introducing a body of oil in the space 4 around the piston ring 3 cushions the ring so that it cannot hammer the sides of the piston ring groove when it changes position during'operation. Ref erence should also be made here to Fig. 4 of the drawing. The edge 21 on piston ring 3 is shown as being sharp. This is done so that the piston ring will act as an oil scraper ring on the clownstroke of the piston and scrape off excess oil, if any, from the interior surface of the cylinder and return such oil to the crankcase for re-use through the groove 4a and the oil drain holes 5. The upper edge 28 on the piston ring 3 is shown suitably rounded or beveled. The purpose of this is to permit the piston ring 3 on the upward stroke of the piston to glide on the oil film on the interior cylinder surface so as to prevent the ring 3 from pushing such oil up into the combustion space of the cylinder. r

The piston ring 3 shown in Fig. 5 is a composite ring made up of two arcuate sections 3a and 3b. The section 3a is split at 30 and is provided with A piston construction comprisingya'i-niston head "having 1a peripheral groove formedl-on the exterior surface" thereof, a, piston ring disposed within thegroove; the resiliency. of; said ring urging it radially outward to allow the exposedside of said ring toslidingly engage theinner surface of the cylinder ring the piston is tooperate, the radial depth of said peripheral groove being such as to provide an-annularcfl chambersurroUnding the rear side of said piston' ring; ahollow wrist'pin providing a confined oil chamber -therein i and-connectingi the piston to the piston rod, diametrically opposed passageways being formed in the piston head connecting the said annular oil chamber tothe oil chamber housed in said wrist pin, a one way check valve disposed in each of said passageways to allow the flow of oil therethrough into said annular oil chamber from said xoil-chamber=housed in the wrist pin whereby the said annular oil chamber is filled with oil during operation of the piston, said valves looking a bodyiof oil in said annular oil chamber to fill "completely the latter when the gas 'pressurein the cylinder exceeds the pressure exerted on the body of'oil contained'in the chamber housed in the-hollow wrist pin, and a spray nozzle mounted on the endof the piston rod which is adjacent to the piston head, said spray nozzle communicating with the. oil chamber housed in'said hollow -pinwhereby a cooling body of oil is Sprayed on the inner surface of the piston head during the power stroke of thepiston'.

6.-A- piston construction comprising a hollow piston head having a peripheral groove'formed on the exterior surface of the sidewall of said "piston head, aresilient piston ring held within saidgroove-the exposed side of said ring being adapted to slidingly engage the inner surface of the-cylinder wherein the-said piston is to operate,

; the radial depth of said peripheral'groove being such as to provide an annular oil chamber surrounding the rear side of said piston ring, a piston-rod; awrist pin providing a confined oil chamber thereinand connecting the piston head to the piston rod, a plurality of passageways being ber in the wrist pin so that the body'cf lubriformedin the hollow piston head connecting the saidannular oil chamber to the oilchamber housed in saidwrist pin, and acne waycheck valve disposed in each of said passageways to allow the flow of oil therethrough into said annu- "lar oil'chamber from said-oil chamber housed in" the wrist pin'whereby the said-annular oil chamber is'filledwith oil during operation of the piston, said valves locking a'body of oil in said annular oil, chamber to fill completely the latter when the pressure in the cylinder exceeds the pistonhead,=a resilient piston ring held within said groove, the exposed side of said ring being adapted to slidingly engage'the inner surface of the cylinder wherein the said piston isto operate, the radial depth of said'peripheral groove being' such as to providiian annular oil chamber surrounding the rear side of said piston ring, a

"piston rod, a wrist pin providing a confined oil chamber therein and connecting the piston head to the piston rod, a'plurality of, passageways:being-formed in the hollow piston head connecting the said annular oil-chamber to the oil chamber housed in said wrist pin, a one way check valve disposed in each of said passageways to allow the fiow'of oil therethrough into said annular oil chamber from said oil chamber housed in the wrist pin whereby the said annular oil chamber is filled with oil during operation of the piston, said valves looking a body of oil in said annular oil chamber to fill completely the latter when thepressure in the cylinder exceeds the pressure exerted on the body of oil contained in the chamber housed in the wrist pin, said body of oil contained in said annular chamber serving to lubricate with an oil film the inner surface of the cylinder wall when the gas pressure above the piston head forces oil through the clearance between the said piston ring and piston head, and a spray nozzle disposed on theiupper end of said piston rod and within the said piston head, said nozzle-being connected by a passageway with the' bo'dyof oil housed in the oil chamber in said wrist pin whereby a cooling spray of oil is forced upon the'inner surface of said hollow piston.

8. A piston construction comprising a hollow piston head having a peripheral groove formed on the exterior surface of the side wall of said piston head, a resilient piston ring held ithin said groove, the exposed side of said ring being adapted to slidingly engage the inner surface of the cylinder wherein the said piston is "to operate, the radial depth of said peripheral groove being such as to provide an annular oil chamber surrounding the rear side of saidpiston'ring, a hollow piston rod, a Wrist pin providing a confined o-il chamber therein and connecting'the piston head to the piston rod; the hollow piston rod being in communication with the'oil'chamcating oil of the associated engine will be forced by the pressure oil feed of the associated engine through said hollow piston rod into said oil chamber in the wrist'pin, a plurality of passageways being formed in the hollow piston head connecting the said annular oil chamber to the said oil chamber housed in the wrist pin,'and a one way check valve disposed 'in eachbf said passageways to allow the flow of oil therethrough into said annular oil chamber from said 'oil chamber housed in the wrist pin whereby the said annular oil chamber is filled with oil during the operation of the piston, said valves locking a body of oil to fill said annular oil chamber when the pressure in the cylinder exceeds the pressure exerted on the body of oil contained in the said chamber housed in the wrist pin, said body of oil contained in said annular chamber serving to lubricate with an oil film the inner surface of the cylinder wall when the gas pressure above the piston head forces 011 through the clearance between the said piston'ring and the piston head. V-

9. A piston construction comprising a hollow piston head having a peripheral groove formed on the exterior surface of, the sidewall of said piston head, a resilient pistonringheld within said groove, the exposed side of said ring being adapted to slidingly engage the inner surface of the cylinder wherein thesaid piston is to operate, the radial depth of said peripheral roove being such as to provide an annular-oil chamber surrounding the rear side of said piston ring,

asseei piston redg wristrinzemv ieee ess fiee il m e h einan rpoe Tether 1 M the piston od: iluralit rass way vb ingformed in the hollowpis head ,connecti the said; annular-,oiI-phamber; o theoil cha beihous si said--w i en r-check airei posedim-eachao, saidazpassaeewa rt al ay when the: pressures in the; cylindenzexceedss the ten-head all? b seated the chamber housed inthe'wristpin said.lbodyof oil; contained in said :annular chamber, servingto lubricate with .an 'oil filmthe .1 inner surface .iof the cylinder @wall .when: the. gas, pressureabove the piston-head forces .oil: through' the stclearance between the said :piston-aring; and piston head, a spray nozzlesdisposed-on. thesupper .end of said piston 1 rodsandi within; the :said: piston head. said nozzletbeingi connecteduby aztpassagewaywithrthetrbodyrof oil housedirrthe oil cham+ 1081 .5 in said: wrist .piniwhereby a cooling spray of oil is forced upon the inner surface-.iofasaw hollow-piston, an'da-spray nozzle disposed on the top of said piston rod and within the hollow piston head, said spray nozzle being in communication with the said oil chamber housed in the wrist pin.

10. In an internal combustion engine lubricated by oil under pressure, a piston construction comprising a piston head having a peripheral groove formed on the exterior surface thereof, a piston ring disposed within the groove, the resiliency of said ring urging it radially outward to allow the exposed side of said ring to slidingly engage the inner surface of the cylinder wherein the piston is to operate, the radial depth of said peripheral groove being such as to provide an annular oil chamber surrounding the rear side of said piston ring, a wrist pin connecting said piston head to the piston rod of the engine, said wrist pin providing a confined chamber to house a body of lubricating oil therein which body of oil is in communication with the pressure oil feed of the engine, passageways being provided for communicating between the body of oil housed in said wrist pin and the body of oil in said annular oil chamber, and one way check valves housed in said passageways for confining the oil in said annular chamber when the gas pressure in the cylinder housing the piston exceeds the pressure of the oil housed in the said confined chamber in the wrist pin. I V

11. In an internal combustion engine lubricated by oil under pressure, a piston construction comprising a piston head having a peripheral groove formed on the exterior surface thereof, a piston ring disposed within the groove, the resiliency of said ring urging it radially outward to allow the exposed side of said ring to slidingly engage the inner surface of the cylinder ring the piston is to operate, the radial depth of said peripheral groove being such as to provide an annular oil chamber surrounding the rear side of said piston ring, means for supplying a body of lubricating oil under pressure to fill said annular chamber, and means for locking the saidbody of oil in said annular chamber when the gas pressure above the piston head exceeds the pressure of said body of oil in said annular chamber, which gas pressure forces a film of lubricating oil from cate with the interior of the piston head so that the lubricating oil scraped from the cylinder by said piston ring will flow through said drain openings into the interior of the piston head.

13. The combination defined in claim 12 wherein the upper edge of the said piston ring is rounded or beveled so that on the upward stroke of the piston, the said piston ring will glide on the oil film on the inner surface of the cylinder to minimize the amount of lubricating oil that may be pushed up into the combustion space of the cylinder.

14. The combination defined in claim 12 wherein the lower edge of the said piston ring is sharp so as to act as an oil scraper on the downstroke of the piston head and scrape off excess oil from the inner surface of the cylinder and return such excess oil to the engine crankcase through said drain holes.

15. The combination defined in claim 12 wherein the upper edge of the said piston ring is rounded or beveled and the lower edge of said piston ring is sharp.

16. In an internal combustion engine lubricated by oil under pressure, a piston construction comprising a piston head having a peripheral groove formed on the exterior surface thereof, a piston ring disposed within the groove, the resiliency of said ring urging it radially outward to allow the exposed side of said ring to slidingly engage the inner surface of the cylinder wherein the piston is to operate, the radial depth of said peripheral groove being such as to provide an annular oil chamber surrounding the rear side of said piston ring, means for supplying a body of lubricating oil under pressure to fill said annular chamber, and means for locking the said body of oil in said annular chamber when the gas pressure above the piston head exceeds the pressure of said body of oil in said annular chamber, which gas pressure forces a film of lubricating oil from said annular chamber through the clearance between the said piston ring and the piston head upon the inner surface of the said cylinder, and said annular oil chamber being so proportioned that a body of lubricating oil remains contained therein after a discharge of the combustion gases from said cylinder. f

17;In an internal combustion engine lubricated by oil under pressure, a piston construction comprising a piston head'having a peripheral groove formed on the exterior surface thereof, 'a piston ring disposed within the groove, the resiliency of said ring urging it radially outward to allow the exposed side of said ring to slidingly engage the inner surface of the cylinder wherein the piston is to operate; the radial depth of'said'peripheral groove beingsuch as to provide an'annular oil chamber surrounding the rear side .of said; piston ring, means for supplying a body'of lubricating oil under pressure to fill said'annular chamber, and means for locking the'said body of oil 'in said annular chamber when the] gas pressure above the piston head exceeds the pressure of said body of oil in said annular chamber, a

which gas pressure forces a film of lubricating oilfrom said annular chamber through the clearance between the said piston ring and the piston head upon the'innertsurface of the said cylinder, and'said annular oil chamber being so proportioned that during a power stroke of the 1 piston the body of lubricating oil housedin said chamher is sufiicient to cushion the said pistonring 'so'that the hammering of the latter against the assent of said ring urging'it' radially outward to allow the exposed side of said ring to slidinglyengage the inner surface of the cylinder wherein the piston is to operatethe radial'depthof said peripheral groove being such as to provide an annular oil chamber surrounding the: rear :side of said pistonring'means for supplying asbody. of

lubricating oil under pressure to 'fill said annular chamber, and means for locking thesaid body. of oil in said annular chamber "when the gas pressure above the piston head exceeds the pressure of said body. of oil in said annular chamber; which gas pressure forces a film of lubricating oil from said annular chamber through the clearance between the'said piston ring and-the piston head upon the inner surface of the said cylinder, said piston ring being roundedgorbeveled at its upper outer edge and its lower outer edge being of square shape. V

- RASMUSM. HVID. 

